Basic Usage¶

The following section describes how to use PowerFlow using the Matlab or Pyhton Interface. It covers how to perform basic power flow calculations in electrical networks. Including loading a network, solving it, and retrieving the results such as node voltages, edge currents and slack powers.

Using PowerFlow in a Matlab script¶

Note

On Ubuntu and possibly other Linux distributions, Matlab may need to be started using a command similar to LD_PRELOAD=/lib/x86_64-linux-gnu/libstdc++.so.6 matlab.

You need the MEX file as well as the PowerFlow.m script in your Matlab PATH to use PowerFlow in Matlab scripts. See the build instructions on how to acquire those.

Loading a network¶

net = PowerFlow("path/to/network.txt", []);

The returned net variable is a pointer/handle to the loaded network. The network will be automatically garbage collected once the handle goes out of scope.

Solve¶

net.solve(S, V);

net.solve performs the power flow calculation. S, V and V_res are complex row vectors. The S vector must contain one complex value per LOAD node in the network.

In a network with n grids, each containing m_1 to m_n number of LOAD nodes, the first m_1 values in the S vector correspond to the load nodes in the first grid, the second m_2 values correspond to the load nodes in the second grid and so on. The LOAD nodes are in turn ordered by their ID, i.e., a LOAD node with ID 0 comes before LOAD node with ID 3 in the S vector. In the same way, V must contain one complex value per SLACK node in the network.

Get LOAD node voltages¶

V_load = net.getLoadVoltages();

net.getLoadVoltages returns the calculated voltages at the LOAD nodes. The V_load vector has the same format as the S vector passed to net.solve.

Get all node voltages¶

V_all = net.getAllVoltages();

Get edge currents¶

I = net.getCurrents();

The elements in the I vector are the currents in the edges in the same order they appear in the Network file. In a network with n grids, each containing m_1 to m_n number of edges, the first m_1 values in the I vector correspond to the edges in the first grid, the second m_2 values correspond to the edges in the second grid and so on.

Get SLACK/SLACK_IMPLICIT node voltages¶

S_slack = net.getSlackPowers();

Reset network¶

net.reset();

All voltages will be set to 1 and all powers will be set to 0.

Passing solver options¶

It is possible to pass additional options to the solver using a settings struct:

% Max number of iterations for the entire network.
settings.max_iterations_total = 10000;

% Max number of iterations for the Gauss-Seidel solver.
settings.max_iterations_gauss = 100000;

% Largest acceptable power mismatch for the Gauss-Seidel solver.
settings.gauss_seidel_precision = 1e-10;

% Max number of iterations for the Backward-Forward-Sweep solver.
settings.max_iterations_bfs = 10000;

% Largest acceptable power mismatch for the Backward-Forward-Sweep solver.
settings.bfs_precision = 1e-10;

% Max number of iterations for the ZBus Jacobi solver.
settings.max_iterations_zbusjacobi = 10000;

% Largest acceptable power mismatch for the ZBus Jacobi solver.
settings.zbusjacobi_precision = 1e-10;

net = PowerFlow("path/to/network.txt", settings);

Thread safety¶

It is NOT safe to load networks simultaneously on different threads!
It is NOT safe to execute net.solve() simultaneously on different threads using the same network handle! However, it is safe to simultaneously execute solve() using different network handles.

Using PowerFlow in a Python script¶

You need to import the PowerFlowPython module to use PowerFlow in Python scripts. See the build instructions on how to acquire the Python module file.

Below is a simple Python script example. For detailed usage instructions, see the Matlab section above.

import PowerFlowPython

settings = PowerFlowPython.SolverSettings()
net = PowerFlowPython.PowerFlow("path/to/grid.txt", settings)

net.solve(V, S)
V_loads = net.getLoadVoltages()